Neural interface device and insertion tools

ABSTRACT

An implanted neural micro interface device is provided. The device comprises microfilaments of various materials and forms embedded within a body. The microfilaments form interaction sites with surrounding neural tissue at their exit points from the implantable body. The body and filaments are configurable in a multitude of positions to provide increased engagement of a given neural tissue section as well as interaction and closed loop feedback between the microfilament sites. Such configurations allow for a range of recording, stimulating, and treatment modalities for the device within research and clinical settings.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims the benefit under 35 U.S.C. §120 as acontinuation application of U.S. patent application Ser. No. 13/725,732filed on Dec. 21, 2012, which in turn claims the benefit under 35 U.S.C.§119(e) as a nonprovisional application of U.S. Prov. Pat. App. No.61/630,944 filed on Dec. 22, 2011, and U.S. Prov. Pat. App. No.61/634,683 filed on Mar. 5, 2012. Each of the aforementioned priorityapplications are hereby incorporated by reference in their entireties.

BACKGROUND

Disclosed herein are neural interface devices and tools used to implantand remove them within nervous systems. More particularly, the inventionrelates to, in some aspects, microelectrode, optogenetic, magnetic, andmicrofluidic array devices with control of recording, stimulating, andtreating a volume of neural tissue and with a design that is easilyconfigured and inserted into a variety of forms dependent upon thedesired research or clinical purpose.

SUMMARY

In some embodiments, disclosed herein is a neural microarray. Themicroarray can include a base member, a plurality of elongate shaftsextending from the base member, the elongate shafts each having asidewall, a channel therethrough; and a plurality of sites incommunication with the channel and spaced apart along the sidewall, thesites configured to stimulate tissue or record a tissue parameter; and aplurality of microfilaments housed within the channel of the pluralityof elongate shafts and extending proximally from at least the basemember and at least one of the microfilaments each extending distallyout each of the plurality of sites. The base member could be flexible orrigid. The base member could include at least one, two, or more sitesdisposed on a surface, such as a tissue-facing surface of the basemember. The sites can be configured such that the microfilaments areconfigured such that the microfilaments extend distally out of each ofthe plurality of sites and are configured to be movable in at least 1,2, 3, 4, 5, 6, or more degrees of freedom when inserted in or proximateneural tissue. In some embodiments, the sites are spaced axially apartalong longitudinal axes of the shafts. The shafts could comprise ahelical shape, or a proximal non-linear portion and a distal linearportion. In some embodiments, the proximal non-linear portion is curved.The microarray could also include a power source operably connected tothe microfilaments, and be connected via wires or wirelessly. Themicroarray could also include an amplifier operably connected to themicrofilaments. The base member can have a major axis that is transverseto the major axis of the plurality of the elongate shafts, wherein athickness dimension of the base member parallel to the major axis of theplurality of the elongate shafts is no more than about 1, 2, 3, 4, 5, 6,7, 8, 9, 10, 15, 20, 25, or 30 times the average diameter of theplurality of microfilaments. In some embodiments, each shaft could havebetween about 2-12 sites, or between about 4-8 sites. In someembodiments, there could be between about 2-96 shafts extending fromeach base member, such as between 2-16 shafts per base member, orbetween about 2-48 shafts per base member.

Also disclosed herein is a method for modulating or monitoring neuralactivity, comprising: providing a microarray comprising a plurality ofhelically-shaped shafts comprising electrodes; inserting at least aportion of the helically-shaped shafts into neural tissue; andactivating the electrodes to modulate or monitor neural activity. Themethod can also include providing an insertion tool comprising a distalzone operably connected to a proximal portion of the microarray; anddisengaging the insertion tool from the microarray following theinsertion step.

Also disclosed herein is a method for modulating neural activity,comprising: providing a microarray comprising a plurality of shaftscomprising magnetic coils; inserting at least a portion of the shaftscomprising the magnetic coils into neural tissue; and activating themagnetic coils sufficiently to modulate neural activity.

In some embodiments, disclosed is a method of modulating neuralactivity, comprising: providing a microarray comprising a first shaftand a second shaft, the first and second shaft each having a sidewalland at least one sidewall opening, the first and second shafts eachcomprising at least one conductive microfilament within a channel of theshafts such that a distal end of the microfilament is proximate thesidewall opening; inserting the first shaft within neural tissue suchthat the sidewall opening is within the neural tissue at a firstlocation; inserting the second shaft at a second position within neuraltissue such that the sidewall opening is within neural tissue at asecond location; and activating the microfilaments, wherein followingactivation of the microfilaments, a constructive energy field effect iscreated within a zone of the neural tissue by the coordinating of themicrofilaments. The microfilaments could be, for example, opticallyconductive, magnetic coils, electrically conductive, or a combinationthereof, or having a stimulatory or recording function, or both. Thefirst shaft and/or the second shaft could include a helical portion.Modulating neural activity can be achieved in a patient having, forexample, a neurologic condition such as epilepsy, depression, or bipolardisorder for example.

Also disclosed herein is a method of modulating neural activity,comprising: providing a microarray comprising a first shaft and a secondshaft, the first and second shaft each having a sidewall and at leastone sidewall opening, the first and second shafts each comprising atleast one conductive microfilament within a channel of the shafts suchthat a distal end of the microfilament is proximate the sidewallopening; inserting the first shaft within tissue such that the sidewallopening is within tissue at a first location; inserting the second shaftat a second position within tissue such that the sidewall opening iswithin tissue at a second location; and activating the microfilaments,wherein following activation of the microfilaments, a constructiveenergy field effect is created within a zone of target tissue by thecoordinating of the microfilaments. The microfilaments could be in thetarget tissue or in the vicinity of the target tissue, or remote fromthe target tissue. In some embodiments, the microfilament sites could bewithin about 20 cm, 15 cm, 10 cm, 9 cm, 8 cm, 7 cm, 6 cm, 5 cm, 4 cm, 3cm, 2 cm, 1 cm, 0.5 cm or less with respect to the target tissue. Insome embodiments, the tissue is bone of the skull, and the target tissueis brain tissue. In some embodiments, the tissue and the target tissueboth comprise neural tissue.

Also disclosed herein is a method for modulating neural activity,comprising: providing an elongate body having a proximal end, a distalend, a sidewall, a lumen at least partially therethrough, and at leastone optical microfilament disposed within the lumen; inserting theelongate body into a first tissue; and activating the opticalmicrofilament to direct light toward a second tissue remote from thefirst tissue, wherein the second tissue comprises neural tissue. Theelongate body can include a coil shape, and in some cases substantiallythe entire elongate body comprises a coil shape. The first tissue couldbe bone, for example.

Also disclosed herein is a neural microarray, comprising a body portion;a plurality of microfilaments; and a microfilament controller, whereinthe body portion is configured to house the plurality of microfilaments,wherein the plurality of microfilaments comprises a first subgroup ofmicrofilaments, the first subgroup of microfilaments being configured tobe activated simultaneously by the controller such that themicrofilaments act in concert to function as a single electrode. Thefirst subgroup of microfilaments can be electrically conductive,optically conductive, or comprise magnetic coils, or a combinationthereof. Furthermore, the microarray can include a second subgroup ofmicrofilaments, the second subgroup of microfilaments being configuredto be activated simultaneously by the controller such that themicrofilaments act in concert to function as a single electrode. Thecontroller can be configured to dynamically increase or decrease thenumber of microfilaments in the first subgroup. The electrode could be astimulating or recording electrode. The microfilaments could comprise arectilinear, triangular, or other cross-section, or a combination ofdiffering cross-sections. In some embodiments, a total area ofnon-conductive space between microfilaments within the body portion isless than about 20%, 15%, 10%, 5%, 3%, 2%, 1%, or less of the total areaof the body portion for housing the microfilaments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an isometric view of microfilaments embedded within acontinuous body.

FIG. 1A shows a top view of microfilaments embedded within a continuousbody.

FIG. 1B illustrates a side view of microfilaments embedded within acontinuous body with recessed areas to provide flexing for conformity tocurved surfaces.

FIG. 1C shows an isometric view of microfilaments embedded within acontinuous body including curved sections to provide custom placement ofpenetrating body sections within tissue.

FIG. 1D illustrates an isometric view of microfilaments embedded withina continuous body with its curved sections flexed to provide desiredentry points for the body's penetrating sections.

FIG. 1E shows a top view of microfilaments 110 embedded within acontinuous body with a central hinge section.

FIG. 1F shows the continuous body with non-linear penetrating sectionsplaced in a circular section of tissue.

FIG. 1G shows the continuous body with non-linear penetrating sectionsplaced in a recessed section of tissue.

FIG. 2 shows an isometric view of microfilaments embedded within acontinuous body with microfilament end sites exposed to the outerenvironment near the end of the penetrating sections of the body. Thesites are positioned and coordinated to create the desired currentcharacteristic at areas of interaction within the penetrating sections,below the tips of the penetrating sections and outside of thepenetrating sections.

FIG. 2A shows an isometric view of microfilaments embedded within acontinuous body with microfilament end sites exposed to the outerenvironment near the end of the penetrating sections of the body. Thesites are positioned and coordinated to create the desired lightcharacteristic at areas of interaction within the penetrating sections,below the tips of the penetrating sections and outside of thepenetrating sections.

FIG. 2B illustrates an isometric view of two continuous bodies withmicrofilaments embedded within them. These continuous bodies arepositioned near one another within tissue so that the current generatedat the microfilament end sites is coordinated to create the desiredcurrent characteristic at areas of interaction.

FIG. 2C illustrates an isometric view of two continuous bodies withmicrofilaments embedded within them. These continuous bodies arepositioned near one another within tissue so that the light generated atthe microfilament end sites is coordinated to create the desired lightcharacteristic at areas of interaction.

FIG. 2D shows an isometric view of microfilaments embedded within acontinuous body with conductive microfilaments coiled within eachpenetrating section before terminating in electrode sites. FIG. 2E showsan isometric view of microfilaments embedded within a continuous bodywith conductive microfilaments coiled within each penetrating sectionand routed back into the joining area of the continuous body. Currentpassed through the conductive coiled microfilaments generates magneticfields. These magnetic fields influence one another and are tuned togenerate desired magnetic stimulation of neural tissue within the volumeof tissue near the penetrating sections.

FIG. 2F shows an isometric view of microfilaments embedded within acontinuous body with conductive microfilaments coiled within eachpenetrating section and routed back into the joining area of thecontinuous body. Current passed through the conductive coiledmicrofilaments generates magnetic fields. These magnetic fieldsinfluence one another and are tuned to generate desired magneticstimulation of neural tissue within the volume of tissue near thepenetrating sections.

FIG. 2G shows an isometric view of microfilaments embedded within acontinuous body with conductive microfilaments coiled within eachpenetrating section and routed back into the joining area of thecontinuous body. Current passed through the conductive coiledmicrofilaments generates magnetic fields. These magnetic fieldsinfluence one another and are tuned to generate desired magneticstimulation of neural tissue within the volume of tissue near thepenetrating sections.

FIG. 2H shows an isometric view of conductive microfilaments embeddedwithin a continuous body. A magnetically conductive microfilamentterminating within each penetrating section of the continuous body issurrounded by a second coiled conductive microfilament. Current passedthrough the coiled filament generates a magnetic field betweenmagnetically conductive microfilament. A magnetic field is alsogenerated at the ends of the coiled microfilament. These magnetic fieldscan be tuned independently or with influence upon one another togenerate desired magnetic stimulation of neural tissue within the volumeof tissue near the penetrating sections.

FIG. 3 shows an isometric view of a microfilament within a continuousbody of a coiled shape.

FIG. 3A shows an isometric view of a microfilament within a continuousbody of a coiled shape rotated into tissue 160.

FIG. 3B shows an isometric view of microfilaments within a continuousbody of a coiled shape. The six degrees of freedom of the microfilamentend sites are illustrated.

FIG. 3C shows an isometric view of microfilaments within a continuousbody of a coiled shape with the end sites of the microfilamentspositioned and coordinated to create the desired current characteristicat points of interaction inside, outside, and below the coiledcontinuous body.

FIG. 3D shows an isometric view of microfilaments within a continuousbody of a coiled shape with the end sites of the microfilamentspositioned and coordinated to create the desired light characteristic atpoints of interaction inside, outside, and below the coiled continuousbody.

FIG. 3E shows isometric views of a helical continuous body embedded withmicrofilaments illustrating its ability to compress and expand, whenembedded in tissue.

FIG. 3F illustrates an isometric view of a helical continuous body withan embedded conductive microfilament generating a magnetic field.

FIG. 3G shows an isometric view of a helical continuous body with anembedded tube circulating a fluid to heat or cool the surroundingtissue.

FIG. 3H shows how a coiled continuous body with an embedded conductivemicrofilament placed within a section of bone generating a magneticfield.

FIG. 3I shows how a coiled continuous body with an embedded opticalfiber microfilament placed within a section of bone generating lightthrough a thin section of bone.

FIG. 3J illustrates a coiled continuous body containing a microfilamentsite near its tip that has penetrated a section of bone.

FIG. 4 shows a continuous body with embedded microfilaments arranged ina densely packed formation.

FIG. 4A shows a continuous body with embedded microfilaments arranged ina densely packed formation with three groups of microfilamentsdischarging current or light.

FIG. 4B shows microfilaments with rectilinear cross sections embeddedwithin a continuous body to decrease gaps between microfilaments endsites.

FIG. 5 illustrates an insertion tool prior to engaging with a continuousbody with embedded microfilaments.

FIG. 5A shows an insertion tool engaged with a continuous body withembedded microfilaments and driving it into tissue.

FIG. 5B shows an insertion tool withdrawing its engagement stem uponreaching full insertion.

FIG. 5C shows an insertion tool withdrawing after disengaging from theinserted continuous body with embedded microfilaments.

FIGS. 6-6D illustrates some embodiments of penetrating section tipgeometry.

DETAILED DESCRIPTION

Neural interfaces are implanted within the nervous systems of animalsand humans to record, stimulate, and treat neural tissue activity.Typically, this occurs within animal research of a variety of fields(e.g. neurological disorders and basic nervous system function) as wellas clinical diagnosis and therapy (e.g., epilepsy). While generallydescribed herein in the context of neural interfaces, any of theembodiments herein can be used or adapted for use with a variety ofneural as well as non-neural organs, tissues, and other anatomicallocations.

Neural interfaces can include a variety of materials and structures. Thelithographic multichannel shank electrode and its variations have foundwide spread use in establishing a neural interface. These electrodes aremost commonly formed using planar, lithographic processes and have beenfabricated in a number of materials including silicon, glass, metal,ceramic and polymers. Conductive channels are lithographically layeredwithin insulators to form multiple recording and stimulation sites on arectangular shank for implantation into neural tissue. Stacking multipleplanar electrodes together has demonstrated three-dimensional electrodesto provide greater recording or stimulation coverage of a given sectionof neural tissue. There are other electrode designs, such as the thinlycoated silicon arrays consisting of approximately one hundred electrodesites located at the individual tips of linear penetrating shanks joinedby a rigid backplate. The tips are inserted into neural tissue to recordor stimulate neural activity. Simple microwire electrodes also exist.These have an individual, or family of microwires with only their tipsexposed (the remainder is surrounded by an insulating coating); as withthe previously mentioned coated silicon arrays, the tips are insertedinto neural tissue to record or stimulate neural activity.

The amount of neural activity recorded, stimulated, or treatedcorresponds to the number and positioning of neural interface devicesites for recording, stimulation, or fluid delivery within a givenneural volume. Researchers and clinicians position neural interfacedevices carefully due to the limited number and configuration of sitesavailable to them on a single micro scale interface (e.g.,microelectrode array).

Unfortunately many current micro neural implants are poorly constructedfor high density recording, stimulating, or treating of neural tissuevolumes. For example, due to the limitations of their linear basedconstruction and structures, existing microelectrodes are constrained inthe positioning of sites, their proximity and angle to one another, andthe end suitability of the device shape for implantation into neuraltissue. These limitations prevent the increase of data acquired as wellas current and future therapies. Current microelectrode designs are alsolimited in controlling the cross sectional shape of penetrating bodiesirrelevant of the number of electrode sites and capabilities. In someembodiments, minimizing the cross sectional thickness reduces theadverse response of the body to neural implants.

Accordingly, in some embodiments, disclosed herein is a tissueinterface, such as a neural interface, that provides six degrees offreedom for placement of microfilament sites (e.g., electrode, lightemitting, magnetic coils, and fluid delivery sites) within an array aswell as options for the structure and shape of its overall shape tooptimize neural implantation. In some embodiments, the sites may belocated either on the distal tip, or along the sidewall of one or moreof the shafts, such as spaced apart at regular or irregular intervals.It can also be advantageous to minimize the body containing themicrofilaments. By minimizing the body containing the microfilamentsboth within and adjacent neural tissue, the neural interface device canhave greater conformity to anatomy and reduces body response duringchronic (e.g., in some embodiments, the electrodes can be implanted forgreater than one day, one week, one month, three months, six months, oneyear, 60 years, or more). In some embodiments, the neural interface iscomposed of only the body and microfilaments; the microfilaments act asstructural elements to provide the desired mechanical characteristics.In some embodiments, the microfilaments exit the baseplate proximallywithin a conduit operably connected to a power source, connector, orcontrol circuitry. In other embodiments, the microfilaments terminateproximally within the baseplate at a wireless power terminal, connector,or control circuitry (not shown). Wireless power can be supplied by, forexample, inductive charging. In some embodiments, the baseplate has theapproximate width to thickness ratio of 4 to 1, or at least about 4 to1, 5 to 1, 8 to 1, 10 to 1, or more.

A flexible baseplate (e.g., joining body) is also advantageous in someembodiments as it allows researchers and surgeons customization ofplacement within the nervous system and increased conformity toanatomical variations. In some embodiments, the joining body isconfigured to be flexible enough to bend around the outer curvature ofneural tissue (e.g., sulcus surface of cortex, circumference of a nerve,or surface of a plexus). In some embodiments the joining body isconfigured to be flexible enough to bend with the motion of neuraltissue due to respiration or containing body acceleration anddeceleration. The ability to shape the tip geometry of penetratingsections and form a penetrating section into a helical form reduces theinsertion force required for insertion of a probe, and thus a reductionin the probe's required cross sectional area can also be advantageous insome cases. In some embodiments, the body has sections of relativelydecreased thickness with respect to other sections, or sections that aremore flexible than other sections to further bend and conform to thetarget anatomy.

In some embodiments, disclosed herein is an implantable neural interfacedevice. The body of the device has various types of embeddedmicrofilaments that act as recording or stimulation electrodes, opticalfibers, or as hollow tubes for media, e.g., fluid delivery. The body ofthe device and its penetrating surfaces can be shaped into advantageousconfigurations for implantation, site density, site interaction, andvarious treatment modalities including recording, stimulating, magneticstimulation, magnetic monitoring, fluid delivery, temperature control,optical stimulation, optical monitoring, and chemical irrigation ofneural tissue. In some embodiments, the body containing themicrofilaments is coated with a drug, such as an antithrombotic agent,an antibiotic, an anti-inflammatory, an anti-epileptic, or achemotherapeutic agent, for example. In some embodiments, theimplantable neural interface device can be placed within any tissuewithin the body dependent upon the desired research or clinical result;including nervous, muscle, connective, epithelial, cardiac, lung, renal,gastrointestinal, and bone tissues. In some embodiments, the implantableneural interface device can be used to diagnosis and/or treat epilepsy,a movement disorder (e.g., Parkinson's Disease), a psychiatric disorder(e.g., clinical depression), the result of a stroke, Alzheimer'sdisease, a cognitive disorder, an anxiety disorder, an eating disorder,an addition or craving, restless leg syndrome, a sleep disorder,Tourette's syndrome, a stress disorder, coma, autism, a hearingdisorder, a vision disorder, retinal degeneration, age related maculardegeneration, dry eye syndrome, a speech disorder, amblyopia, headaches,temporomandibular joint disorder, pain (e.g., phantom limb pain andacute or chronic pain) such as sciatica, urinary or fecal incontinence,sexual dysfunction including erectile dysfunction, bone diseaseincluding osteoporosis or fractures, arthritis, tendinitis, the resultof ligament or tendon damage, and paralysis (e.g., facial nerveparalysis and spinal paralysis). In some embodiments, the implantableneural interface device can be used to provide control of a prostheticsuch as a limb or an external computer.

In some embodiments, systems and methods as disclosed herein canmodulate neural tissue, and have a stimulatory or inhibitory effect.Neural tissue is specialized for the conduction of electrical impulsesthat convey information or instructions from one region of the body toanother. About 98% of neural tissue is concentrated in the brain andspinal cord, which are the control centers for the nervous system.Neurons transmit signals as electrical charges which affect their cellmembranes. A neuron has a cell body (soma) that contains a nucleus. Thestimulus that results in the production of an electrical impulse usuallyaffects the cell membrane of one of the dendrites, which then eventuallytravels along the length of an axon, which can be a meter long. Axonsare often called nerve fibers with each ending at a synaptic terminal.Neuroglia are cells of the CNS (central nervous system) and PNS(peripheral nervous system) that support and protect the neurons. Theyprovide the physical support for neural tissue by forming myelinsheaths, as well as maintaining the chemical composition of the tissuefluids and defending the tissue from infection. Schwann cells arespecialized PNS cells that form myelin sheaths around neurons. Neurons(nerve cell) include a cell body that contains the nucleus and regulatesthe functioning of the neuron. Neurons also include axons which arecellular process (extension) that carry impulses away from the cellbody. Neurons also include dendrites which are cellular process(extension) that carry impulses toward the cell body. A synapse is aspace between axon of one neuron and the dendrite or cell body of thenext neuron—transmits impulses from one neuron to the others.Neurotransmitters are chemicals released by axons and transmit impulsesacross synapses.

In certain coiled configurations, the conductive embedded microfilamentscan also generate magnetic fields. Once in an implanted position withinneural tissue, a current run through a coiled conductive microfilamentgenerates a magnetic stimulation of a targeted volume of neural tissue.In addition to stimulating neural tissue, the magnetic field could beused to inhibit neural activity by blocking the typical mechanisms ofneural communication. The transmission of a magnetic field into neuraltissue can also be achieved by placing the coiled microfilament in closeproximity to neural tissue (e.g., within bone such as the cranium).These magnetic fields can range between 0.4 μT-0.01 T. The magneticfield can alternate in a variety of waveforms with the maximum strengthranging between 0.1 μT to 2 T, such as no more than about 0.1 mT, 1 mT,10 mT, or 100 mT. The coiled microfilaments can also be used to monitormagnetic fields that are, for example, generated by the neural interfacedevice or by an external source. In addition to stimulating neuraltissue, the magnetic field could be used for other purposes, such asinhibiting neural activity by blocking the typical mechanisms of neuralcommunication.

In some embodiments, provided is a closed loop control system forstimulating and monitoring neural activity. To meet this objective,microfilaments are embedded in various body configurations with sixdegrees of freedom to provide many system options for interacting withneural tissue. As an example, this would enable the data collected froma first recording microfilament (or external source) to help guide theoutput of a second stimulating microfilament dynamically and on-the-fly.

The approximate diameter of circular microfilaments for conductingelectrical current is between 1 μm and 250 μm, such as no more thanabout 25 μm, 50 μm, or 75 μm. For electrical stimulation, larger sitesup to 50 μm would be advantageous to achieve surface areas that meetuseful stimulation current requirements without a coating. Theapproximate diameter of circular microfilaments for conducting ormonitoring light is between is 0.1 μm to 250 μm, such as no more thanabout 25 μm, 50 μm, or 75 μm. The approximate diameter of circularmicrofilament tubes for delivering or circulating gases, fluids, andmixtures in some embodiments is between 1 μm to 100 μm, or no more thanabout 50 μm, 75 μm, 100 μm, or 150 μm. Microfilaments can also be placedwithin a packed geometry that allows for a tapering of the penetratingarea cross sections to reduce the cross sectional area and thus longterm adverse neural tissue response. In some embodiments, themicrofilaments can extend outward from the body's surface; these sitescan be formed (e.g., bent or flattened) to provide desired functionalcharacteristics.

The array body can take multiple forms including penetrating structureswith microfilament sites and joining sections to optimize placementwithin the nervous system. An approximate cross sectional area of apenetrating array body in some embodiments is 1 μm² to 0.2 mm²,preferably up to approximately 7850 μm². For large area coverage as inelectrocorticography, larger body areas up to approximately 100 cm² ormore could be advantageous to collect more data from the outer surfaceof a neural tissue section.

The array body can also take on a substantially helical shape thatallows a novel insertion technique of screwing, e.g., circumferentially,into neural tissue. This requires a lower insertion force than a linearbody shape and provides a more advantageous angle of attack. Some neuralimplantation surgeries involve significant motion (e.g., due torespiration), a helical shape is capable of absorbing this motion whilebeing rotated into position. The lower insertion force required of thehelical inserter provides an opportunity for increased control duringthe insertion procedure. Once inserted, the helical form can also flexwith neural tissue with a tuned spring coefficient as well as bend andflex near the point of entry as with a typical electrode. The helicalform can be between 0.1 mm and 20 mm in length with a 1.0 μm² to 0.2mm², in some cases up to approximately 7850 μm² or more cross sectionalarea with a variety of shapes to further reduce insertion force andtissue damage (e.g. a tapering cross section).

The array body can also take on non linear shapes, which allow novelinsertion techniques into difficult areas to access within surgery. Acurved shape can be rotated into position where a linear angle of attackis unavailable. The array body can also have one, two, or more curveslocated at different positions (e.g., proximal, midportion, or distal)to aid in anchoring to neural tissue or bone, while there may be alinear segment distal to, and/or proximal to the curved segment.

One advantage of the device in some embodiments is the wide range ofmaterials and components available for the microfilaments and body toimprove insertion conditions and long term performance within a nervoussystem. The microfilaments can be formed from gold, platinum, platinumiridium, carbon, stainless steel, steel, aluminum, conductive polymers,polymers, organic materials or any other material known to those skilledin the state of the art. The body can be formed from polymers, metals,composites, organic materials, or any other material known to thoseskilled in the state of the art. Another advantage of the device in someembodiments is the ability to combine within a volume of neural tissuemany different interface types (e.g., electrodes with optical fiberswith fluid delivery); this provides a novel approach to research andclinical treatment within a single body. Yet another advantage of thedevice in some embodiments is the many shapes possible with themicrofilament containing body. The shape of the body can be customizedfor a given procedure, area of anatomy, and functional purpose. Anexample of an advantageous form is a substantially coiled shape thatutilizes a conductive filament to produce a magnetic field for neuralstimulation. The coiled shape also has the advantage of a lowerinsertion force, as well as compression or extension after implantationto more closely move with the surrounding neural tissue. Yet anotheradvantage in some embodiments is the placement of coiled conductivemicrofilaments within a penetrating body. Positioning of the coiledconductive microfilaments and current selected will generate magneticfields of varying characteristics within neural tissue; this hasadvantageous effects including the blocking of tissue electricalactivity or stimulation. A three-dimensional view of an example of aneural interface device 100 is shown in FIG. 1. In general, two distinctparts of the device can be distinguished: microfilaments 110 and a body,such as a continuous body 120 surrounding the microfilaments.Microfilaments in some embodiments can be conductive materials thattransmit current. In some embodiments, microfilaments can be opticalfibers that transmit or monitor light. In still other embodiments,microfilaments can be hollow tubes that transport fluids and mixtures.In some embodiments, a device 100 could include a combination of one,two, or more of conductive, optical, or hollow tube microfilaments orothers. In some embodiments the continuous body 120 includes penetratingstructures. The continuous body 120 can be a single material from thepenetrating tips 121 to the end of its flexible cable 122, e.g.,integrally formed. The continuous body can have areas as thin as, oreven thinner than the microfilament 110. In some embodiments, thecontinuous body could be integrally formed, or formed as part of aplurality of bodies joined together, so long as it is physicallycontinuously connected together as a whole.

FIG. 1A illustrates a plurality of microfilaments 110 embedded withinthe continuous body 120. The top view shows the orientation ofmicrofilaments 110 to provide space for one, two, or more movable walls,e.g., hinged sections 130 with wall thicknesses between 0.5 μm and 1000μm in some embodiments to provide flexibility. The baseplate 120 couldhave a first section having a first thickness, and a second sectionhaving a second thickness that is more or less than the first thickness.

FIG. 1B illustrates a side view of microfilaments 110 embedded withinthe continuous body 120. In some embodiments, the microfilaments can bemolded or otherwise fixed in place and exit the continuous body at anexit port or opening in the body and have a distal end that can be flushwith the continuous body outer surface at sites 140. In someembodiments, the site need not include a physical opening, for examplefor an optical fiber that terminates within a site configured to radiateor monitor light through the baseplate and/or shaft (e.g., an opticallytransparent area). In other words, the site 140 can be configured withor without a physical opening, but just be configured to transmit energyor monitor a parameter.

Conductive microfilament sites 140 are capable of recording orstimulating electrical activity nearby within tissue. Optical fibermicrofilament sites are capable of stimulating neural activity utilizingoptogenetic techniques (i.e. transfection of tissue to respond toexposure to a specific form of light). Microfilaments can also form tipsof penetrating sections 123 of continuous body 120.

FIG. 1C illustrates another embodiment of microfilaments 110 embeddedwithin a continuous body 120 with curved sections 124 ending inpenetrating sections (that could be linear as illustrated) 123 toprovide flexibility. The curved sections 124 can be straightened (e.g.,temporarily) or malleable to provide multiple options for placing thepenetrating sections 123. FIG. 1D shows the penetrating sections 123 ofa continuous body 120 placed within a section of tissue 160.

In some embodiments, the continuous body has one, two, or more shapedvoids in desired locations to increase the continuous body's ability tocollapse, fold, form, or otherwise shape itself to a targeted area oftissue. In some embodiments, the shaped voids can be used in conjunctionwith flexible or movable sections to increase the continuous body'scapability to fold or collapse within six degrees of freedom and betterfit the wide variety of target tissue shapes. For example, a body couldhave a first section that is more flexible than a second section, orfirst and second sections connected by a third section that is moreflexible than the first and second sections.

FIG. 1E illustrates another embodiment of microfilaments 110 embeddedwithin a continuous body 120 with a hinge, joint, or otherwise movablesection 130 with wall thickness between 0.5 μm and 1000 μm in somecases. The hinge could be, for example, a fold, living hinge or amechanical-type hinge. The section 131 can be, for example, a void inthe continuous body 120 that allows both the continuous body 120 and themovable section 130 to have greater flexibility. FIG. 1F shows thecontinuous body 120 with non-linear penetrating sections rotated topenetrate a circular section of tissue 160. FIG. 1G shows non-linearpenetrating sections rotated to penetrate a depression within a sectionof tissue 160 (e.g., sulcus of the cortex).

FIGS. 2-2H are schematic diagrams showing how different embodiments ofmicrofilament sites 140 can interact with each other within an array toillustrate using one or multiple types of microfilaments in an arraythat interacts with itself. FIG. 2 shows a continuous body 120 with aplurality of, e.g., three shafts having penetrating sections andmicrofilament sites 140. The microfilament sites 140 are positioned andcoordinated relative to one another so that they interact at specificareas. Microfilaments formed from different or the same materials can beused within the same continuous body 120.

In some embodiments, microfilament sites 140 form current source andsink pairs as indicated by lines 201. The microfilament site pairs canbe activated at different times such that the cumulative charge withinregion 202 reaches a threshold to cause stimulation, while the chargeoutside region 202 remains below activation threshold. Multiple methodsexist for activating the sink/source pairs including a linearlysequential scan, a scan to reduce adjacent interactions, or aninterleaving bipolar stimulation scheme with all of the cathodic pulsesoccurring before the anodic pulses for example.

In some embodiments, a microfilament site 140 acts as a current source(or sink) while multiple sites 140 act as a current sink (or source).Lines 204 display this one-to-many (e.g., more than one, two, three,four, or more) pairing between sites 140. This could also be extended toa few-to-many pairing (e.g., two-to-five, three-to-three, three-to-ten,or any other combination). This configuration generates activationregion 206 in the area of larger charge concentration.

The sites 140 could be on the distal end of a given shaft, and/or on thesidewalls of a given shaft. In some embodiments, each shaft could have2, 3, 4, 5, 6, 7, 8, 9, 10, or more sites each regularly or irregularlyspaced apart axially along the longitudinal axis of the shaft, or alonga curved length of a shaft for non-linear embodiments. In someembodiments, a first shaft could have the same number, more, or lesssites than a second shaft. Each site could have the same or differentattributes, e.g., a first site that is electrically active, a secondsite that is optically active, a third site that is magnetically active.Some sites could function as stimulatory sites, while other sites couldfunction as recording sites.

In some embodiments, two (or more) sites flow charge 208 between eachother. The tissue within high charge region 208 activates thecorresponding tissue, which could exist within, outside, or below thepenetrating body.

In some embodiments, the microfilament sites 140 configured to stimulateor record tissue parameters are located in the body itself 120 (e.g.,one, two, or more sites 140 residing on a surface, such as adistal-facing surface of the baseplate, which can have a major axis thatis generally parallel to the target tissue surface in some embodiments)and interact through the surface of the tissue with the penetratingbodies or other surface located sites 140. In all of these methods, anexternal electrode (not shown) could be used to collect any unbalancedcharge.

FIG. 2A shows waves of energy, such as light 150 generated bymicrofilament sites 140 interfering with one another within areas 155.In other words, activation of a first microfilament site can create afirst energy zone, and activation of a second microfilament site spacedapart from the first microfilament site can create a second energy zone.An interference zone (either constructive or destructive) can be createdwhere the first energy zone and the second energy zone intersect. Insome embodiments, the energy, e.g., light intensity increases atintersections of constructive interference within areas 155. In someembodiments, the areas of light interference 155 can be used to increasethe light intensity beyond the threshold required to modulatetransfected tissue using optogenetic techniques. As such, a more focusedarea of constructive interference 155 can be created by the intersectionof two or more beams 150, focusing the treatment of tissue within thatarea. Combining different wavelengths (e.g., colors) of light generatedat sites 140 can create desired wavelength combination (e.g., colors)within areas of light interference 155. Areas of light interference 155are controllable volumes of tissue modulation dependent upon theintensity of the light sources, wavelength of light sources, positioningof microfilament sites 140, focal characteristics of light sources, andfrequency of light generation. In some embodiments, the microfilamentsites 140 can also be positioned within the joining section ofcontinuous body 120 to provide additional options for areas of lightinterferences 155. FIG. 2B shows the use of first and second continuousbodies 120 spaced apart and positioned relative to one another so thattheir respective microfilament sites 140 create a charge region 208within a section of neural tissue 160. FIG. 2C shows the use of twocontinuous bodies 120 positioned relative to one another so that theirmicrofilament sites 140 create an additive light area of interaction 155within a section of neural tissue 160.

FIGS. 2D-2G illustrate the use of coiled microfilaments 170 withincontinuous bodies 120 to generate magnetic fields 180 that stimulateneural tissue. Dependent upon the positioning of the coiledmicrofilaments 170 within the continuous body 120, the magnetic fields180 interact with one another in different areas. FIG. 2H illustrates amagnetically conductive microfilament 110 within a continuous body 120that is encircled by a coiled microfilament 170. A current passingthrough microfilament 170 emits a first magnetic field 180 as well asgenerating an additional second magnetic field 180 between microfilament110.

In some embodiments, the continuous body 120 is in a coiled form (e.g.,a helix). A coiled continuous body provides a number of possibleadvantages, including six degrees of freedom for the placement ofmicrofilament sites 140, as described in additional detail herein.

FIG. 3 shows an isometric view of a microfilament 110 within acontinuous body 120 of a coiled shape. FIG. 3A shows an isometric viewof a microfilament 110 within a continuous body 120 of a coiled shaperotated into tissue 160.

FIG. 3B illustrates the six degrees of freedom possible formicrofilament sites 140 within a coiled continuous body 120. Thesedegrees of freedom of site 140 include, for example, translation along,and extension and/or retraction from the surface of continuous body 120.They also include rotation of site 140 such that it can be oriented topoint in the desired direction or be located at the desired position onthe surface (e.g., on top or internal surface of the continuous body).FIG. 3C shows embodiments of microfilament site 140 positioning togenerate charge region 208 within, below, and outside of the continuousbody. Although not shown, positioning and coordination of microfilamentsites 140 to generate charge region 208 can be similar to theinteraction methods described in FIG. 2. FIG. 3D shows a helical shapedcontinuous body 120 with waves of light 150 generated by microfilamentsites 140 interfering with one another within areas 155. In someembodiments, the areas of light interference 155 can be used to increasethe light intensity beyond the threshold required to modulatetransfected tissue using optogenetic techniques. In other embodiments,combining different colors of light generated at sites 140 can createdesired colors within areas of light interference 155. Areas of lightinterference 155 create controllable volumes of tissue modulationdependent upon the intensity of the light sources, colors of lightsources, positioning of microfilament sites 140, focal characteristicsof light sources, and frequency of light generation.

FIG. 3E shows a coiled continuous body 120 compressing and expandingwith the deformation of the neural tissue 160 it is implanted within.

FIG. 3F illustrates a conductive microfilament 110 within a coiledcontinuous body 120 with a microfilament site 140 near the tip. Currentpassing through the microfilament generates a magnetic field 180 thatstimulates surrounding tissue. In this embodiment, the current is alsodischarged into the tissue at the microfilament site 140. FIG. 3G showsa coiled continuous body 120 containing a hollow tube microfilament 190therein that circulates a media, such as a fluid within the continuousbody to cool or heat surrounding tissue.

FIG. 3H shows how a coiled continuous body 120 containing a conductivemicrofilament 110 can also be placed within a section of bone 200 togenerate a magnetic field 180 that stimulates nearby neural tissue. Anexternal site completes the current path with the current flowingthrough the bone. FIG. 3I shows how a coiled continuous body 120 with anembedded optical fiber microfilament placed within a section of bone 200generates light through a thin section of bone. In some embodiments, thebone 200 is shaped near the microfilament site before the body 120 isplaced in position. Shining light through the bone can in some casesmodulate the nearby neural tissue 160 using optogenetic techniques.

FIG. 3J illustrates a coiled continuous body 120 containing a site 140near its distal tip that has penetrated a section of bone 200 to beproximate neural tissue. In some embodiments, a conductive microfilamentsite 140 can stimulate or record nearby neural tissue 160. In anotherembodiment, an optical fiber microfilament site 140 can stimulate nearbyneural tissue using optogenetic techniques (i.e., transfection of tissueto respond to exposure to a specific form of light).

FIG. 4 shows a dense packing of microfilament sites 140 within acontinuous body 120. FIG. 4A illustrates groupings 300 of a plurality ofthe microfilament sites 140 that provide customized recording orstimulation dependent upon specific neural tissue requirements. Thegroupings 300 provide a more precise, customizable, and responsiveinteraction with neural tissue than standard pre-shaped circular sites.The sites 140 can be configured to be linked together electrically oroptically, such as via a controller for example, such that each grouping300 functions as a single site. In some embodiments, such configurationscould advantageously allow for customized site shapes that couldstimulate along a specific target area of the brain; fine control oversite location since the grouping 300 can be moved by one unit in alldirections; or dynamic movement or a change/reassignment inidentification within a particular grouping via a controller in realtime to follow an area of interest (e.g., migrating the grouping suchthat a first microfilament is part of the first subgroup at a firstpoint in time, but at a second point in time, the first microfilament isno longer part of the first subgroup, and a second microfilament becomespart of the first subgroup. To pack microfilament sites 140 more tightlytogether, in some embodiments, microfilament cross sections 110 can havevarying cross sections including different circular sizes as well asrectilinear and triangular. In any embodiments disclosed herein, thearray of microfilaments could include one, two, or more different typesof microfilaments, e.g., electrically active, optically active,magnetically active, hollow tube microfilaments, and the like. FIG. 4Bshows an embodiment of these sites packed within an area of the body orhousing to reduce the non-conducting area or free space betweenmicrofilaments/electrodes to less than about 10%, 5%, 2%, 1%, or less,or between about 1-10% of the total device area. In some embodiments, itis advantageous to link recording microfilament sites 140 beforeamplification. These site shapes can also be created using lithographicmanufacturing as well as other processes understood by thoseknowledgeable within the state of the art. In some embodiments, a systemcould include a processing unit or other features as described, forexample, in U.S. Pat. No. 7,212,851 to Donoghue et al., herebyincorporated by reference in its entirety.

An embodiment of a neural microarray insertion and removal tool andmethod will now be described. FIG. 5 illustrates an insertion holder 500with stem 510 above a continuous body 120 with embedded microfilamentsand an opening 125. FIG. 5A shows an insertion holder 500 engaging itsstem 510 with a corresponding opening 125 and driving the continuousbody 120 into neural tissue 160. FIG. 5B shows the insertion holder 500retracting its stem 510 from the opening 125. FIG. 5C illustrates theinsertion holder 500 disengaging and withdrawing from contact with thecontinuous body 120. In some embodiments, the engagement/disengagementmechanism could include threads, a friction fit surface, a lock, movablejaws, electromagnets, or the like. A reverse process can be used suchthat the tool is configured to remove the continuous body from tissueonce stimulation or recording is no longer required.

FIG. 6 illustrates some embodiments of continuous body 120 penetratingsection tip geometry 129. Rounded outer surface 300 joining with tip isbetween approximately 5 μm and 400 μm, with the width between 5 μm and200 μm. FIG. 6A illustrates concavity 301, which is between a radius of2.0 μm and 1000 μm. FIG. 6B. illustrates rounded tip 302, which has anapproximate radius between 0.1 μm and 125 μm. FIG. 6C illustrates thread303, which is advantageous in some embodiments as it provides initialpenetration of outer tissue coverings (e.g., dura) preceding a linearinsertion; it can have, in some embodiments, an outer diameter between10 μm and 200 μm, and a thread pitch between 3.0 μm and 100 μm. FIG. 6Dillustrates double concavity 304, with each having a radius of curvatureof approximately 2.0 μm to 1000 μm.

Although certain embodiments of the disclosure have been described indetail, certain variations and modifications will be apparent to thoseskilled in the art, including embodiments that do not provide all thefeatures and benefits described herein. It will be understood by thoseskilled in the art that the present disclosure extends beyond thespecifically disclosed embodiments to other alternative or additionalembodiments and/or uses and obvious modifications and equivalentsthereof. In addition, while a number of variations have been shown anddescribed in varying detail, other modifications, which are within thescope of the present disclosure, will be readily apparent to those ofskill in the art based upon this disclosure. It is also contemplatedthat various combinations or subcombinations of the specific featuresand aspects of the embodiments may be made and still fall within thescope of the present disclosure. Accordingly, it should be understoodthat various features and aspects of the disclosed embodiments can becombined with or substituted for one another in order to form varyingmodes of the present disclosure. Thus, it is intended that the scope ofthe present disclosure herein disclosed should not be limited by theparticular disclosed embodiments described above. For all of theembodiments described above, the steps of any methods need not beperformed sequentially.

What is claimed is:
 1. A neural microarray, comprising: a base member; aplurality of elongate shafts extending from the base member, theelongate shafts each having a sidewall, a channel therethrough; and aplurality of sites in communication with the channel and spaced apartalong the sidewall, the sites configured to stimulate tissue or record atissue parameter; and a plurality of microfilaments housed within thechannel of the plurality of elongate shafts and extending proximallyfrom at least the base member and at least one of the microfilamentseach extending distally out each of the plurality of sites.
 2. Themicroarray of claim 1, wherein the base member is flexible.
 3. Themicroarray of claim 1, further comprising at least one site disposed ona surface of the base member.
 4. The microarray of claim 1, wherein thebase member comprises a hinged portion.
 5. The microarray of claim 1,wherein the sites are configured such that the microfilaments extendingdistally out of each of the plurality of exit ports are configured to bemovable in at least 6 degrees of freedom when inserted in or proximateneural tissue.
 6. The microarray of claim 1, wherein the sites arespaced axially apart along longitudinal axes of the shafts.
 7. Themicroarray of claim 1, wherein the shafts comprise a helical shape. 8.The microarray of claim 1, wherein the shafts comprise a proximalnon-linear portion and a distal linear portion.
 9. The microarray ofclaim 1, wherein the proximal non-linear portion is curved.
 10. Themicroarray of claim 1, further comprising a power source operablyconnected to the microfilaments.
 11. The microarray of claim 1, whereinthe power source is wirelessly connectable to the microfilaments. 12.The microarray of claim 1, further comprising an amplifier operablyconnected to the microfilaments.
 13. The microarray of claim 1, whereinthe base member has a major axis that is transverse to the major axis ofthe plurality of the elongate shafts, wherein a thickness dimension ofthe base member parallel to the major axis of the plurality of theelongate shafts is no more than about 10 times the average diameter ofthe plurality of microfilaments.
 14. A method for modulating ormonitoring neural activity, comprising: providing a microarraycomprising a plurality of helically-shaped shafts comprising electrodes;inserting at least a portion of the helically-shaped shafts into neuraltissue; and activating the electrodes to modulate or monitor neuralactivity.
 15. The method of claim 14, further comprising: providing aninsertion tool comprising a distal zone operably connected to a proximalportion of the microarray; and disengaging the insertion tool from themicroarray following the insertion step.
 16. A method of modulatingneural activity, comprising: providing a microarray comprising a firstshaft and a second shaft, the first and second shaft each having asidewall and at least one sidewall opening, the first and second shaftseach comprising at least one conductive microfilament within a channelof the shafts such that a distal end of the microfilament is proximatethe sidewall opening; inserting the first shaft within neural tissuesuch that the sidewall opening is within the neural tissue at a firstlocation; inserting the second shaft at a second position within neuraltissue such that the sidewall opening is within neural tissue at asecond location; and activating the microfilaments, wherein followingactivation of the microfilaments, a constructive energy field effect iscreated within a zone of the neural tissue by the coordinating of themicrofilaments.
 17. The method of claim 16, wherein the microfilamentsare optically conductive.
 18. The method of claim 16, wherein themicrofilaments comprise magnetic coils.
 19. The method of claim 16,wherein the microfilaments are electrically conductive.
 20. The methodof claim 16, wherein the first shaft and the second shaft comprise ahelical portion.